Rough running 69

[rua69z]

I am looking for a little input on my car I have a 69 Z with a 302 and pretty much all stock components carb, intake, solid lifters etc. i just got the car running this summer for the first time and have been running the Shell Rotella and a 110 and 93 octane mixture. The car has been running great and has about 1000 miles on it I live in S.D. and the temp here has dropped to aroung 50 degrees and I started it lastweekend and it started running different I noticed it does not idle at all and it seems to be running rich now and developed a slight miss when running. I did quit using the 110 mixture on the last tank so it is about all 92-93 octane pump gas now. If I start the car and run it up to 1000 rpm it seems ok but again seems to be really rich running. I have not touched the carb at all and it continues to run this way after it is warmed up. Any thoughts or suggestions?

[JohnZ]

Have you checked the tune-up basics (dwell, timing, idle mixture screw adjustment, choke operation/adjustment, vacuum leaks, plug wire condition, plug condition, etc.) ?

[rua69z]

John
As you can see in my rant I was concerned as it was running great and I shut it off and started it a week later and this started to happen. I have been freaked out about wiping my cam and was worried that my be the issue but I have been doing some of the things you aske about and I think it is down to a carb issue I held the tac at a steady 1000 rpm and it ran smooth but it seems to be rich I have a pretty good Holley carb guy here so maybe he has an answer.

thanks for your response

[Oaklyss]

Check your power valve. It may have loosened or blown. Replace it and install all new gaskets. Keep the fuel bowl screws tight. Good to add the Holley blow out protection check valve into the carb base. These long duration cams will blow out the power valve with every small backfire or hic-cup.

[m22mike]

Good advice to check the power valves, just went through this this summer. Had one leaking and one coming loose, ran like crap @ idle, real rich, ran OK while uder some load and as soon as I would stop it would stall. Carb had 12 years on it.

Mike

[rua69z]

It sounds exactly like mine so I will look at the power valves as soon as I know what they are? Can anyone suggest a good book on rebuilding of Holley carbs or a carbs for dummies book?

thanks Jim

[JohnZ]

It sounds exactly like mine so I will look at the power valves as soon as I know what they are? Can anyone suggest a good book on rebuilding of Holley carbs or a carbs for dummies book?

thanks Jim

Super Tuning and Modifying Holley Carburetors, by Dave Emanuel; S-A Design books, #SA-08, ISBN 1-884089-28-3. Lots of Holley books at Border's, etc.

[rua69z]

Thank you I will go find one.

Jim S